1. Field of the Invention
This invention is in the field of coal gasifiers and coal burners utilizing cyclic compression and expansion to force reactant gases into the coal pores and to expand reacted gases out of the coal pores.
2. Description of the Prior Act
The following U.S. Patents describe several types of cyclic char fuel reaction plants, and are examples of such plants with which the devices of this invention are usable:
U.S. Pat. No. 4,455,837; J. C. Firey, June 26, 1984 PA0 U.S. Pat. No. 4,484,531; J. C. Firey, Nov. 27, 1984 PA0 U.S. Pat. No. 4,509,957; J. C. Firey, Apr. 9, 1985 PA0 U.S. Pat. No. 4,568,361; J. C. Firey, Feb. 4, 1986
In all of these examples cyclic char fuel reaction plants the gaseous reactants, such as air, are compressed into the pore spaces of the char fuel contained within several pressure vessel containers. Primary reaction of the gaseous reactants with the char fuel occurs within the pore spaces during compression. Expansion of these primary product gases then occurs out of the pore spaces of the char fuel. In some forms of cyclic char fuel reaction plant the primary product gases are further reacted with additional reactant gases in a secondary reaction within a secondary reaction chamber during expansion. This cycle of gas compression followed by expansion is repeated for each of the char fuel containers, with fresh gaseous reactants being supplied for each compression and with final product reacted gases being removed during each expansion. The descriptions of cyclic char fuel reaction plants contained in the above listed U.S. Patents are incorporated herein by reference thereto. The compressors of these plants are separate from the expanders thereof, but may be driven thereby, as for example where a centrifugal compressor is driven via its input shaft by the output shaft of a gas turbine engine expander.
The compressor means of these cyclic char fuel reaction plants comprise one or more stages, as defined in the material incorporated by reference, and each such stage has a delivery end outlet at its high pressure end through which the compressed gas may flow out of the stage and into a connected char fuel container. The expander means of these cyclic char fuel reaction plants may be a work producing engine and comprise one or more stages, as defined in the material incorporated by reference. Additional detailed descriptions of compressor means and expander means and compressor drive means are presented in the material incorporated by reference, for example in U.S. Pat. No. 4,509,957, col. 15, line 11, through col. 17 line 44.
Several char fuel containers are used on these cyclic char fuel reaction plants and these are pressure vessels whose number at least equals the sum of the number of compressor stages plus the number of expander stages. Each of these containers is fitted with a refuel means for adding char fuel into the refuel end of the container and an ash removal means for removing ashes or spent char fuel material from the ash removal end of the container.
Each container has separate changeable gas flow connections to each delivery end outlet of each compressor stage and these gas flow connections can be opened or closed while the plant is operating. These changeable gas flow connections are opened and closed by a means for opening and closing which is controlled so that each container is opened for a time period to each delivery end outlet of each stage of the compressor, in a sub sequence of time periods of open gas flow connections to compressor stages, proceeding in time order of increasing compressor stage delivery pressure. During any one time period of this sub sequence of time periods each container is open gas flow connected to but one compressor stage delivery end outlet and each compressor stage delivery end outlet is open gas flow connected to but one container. Additional detailed descriptions of char fuel containers and changeable gas flow connections are presented in the material incorporated by reference, for example in U.S. Pat. No. 4,509,957, col. 14, line 46 through line 58, and col. 18, line 39 through line 52.
As used herein and in the claims the term char fuel is as defined in U.S. Pat. No. 4,509,957, col. 2, line 58 through line 68, and in U.S. Pat. No. 4,455,837, col. 4, line 8 through line 16, and this material is incorporated herein by reference.
As used herein and in the claims the terms oxygen gas, and a gas containing appreciable oxygen gas, are as defined in U.S. Pat. No. 4,509,957, col. 3, line 1 through line 8 and in U.S. Pat. No. 4,455,837, col. r, line 1 through line 7, and this material is incorporated herein by reference.
Prior art cyclic char fuel reaction plants have described various methods for starting the plant up. Char fuels must be brought up to a temperature at which they will react rapidly with oxygen gas in adjacent compressed gases before the plant is started and capable of running itself. This preheating of the char fuel is the slowest step of the startup process and it would be desirable to have available startup methods which more quickly heated up the char fuel to this rapid reaction temperature. One startup method of the prior art uses preheated air or oxygen rich gas as the gas compressed into the char fuel pores, this gas preheating being done by electrical resistance heaters or combustion fired heat exchangers as the gas flows from the compressor into the char fuel containers. This air preheating startup method is described in U.S. Pat. No. 4,509,957, col. 7, line 36 through line 63 and in other portions of the prior art references incorporated herein by reference. Another startup method of the prior art burns a fuel gas with spark ignition at the end of a borehole into an underground coal seam to preheat the gases being compressed into the pores of the coal within the underground seam. This gas fired startup method is described in U.S. Pat. No. 4,509,957, FIG. 6, and Col. 18 line 3 through line 29.